Click for next page ( 22


The National Academies | 500 Fifth St. N.W. | Washington, D.C. 20001
Copyright © National Academy of Sciences. All rights reserved.
Terms of Use and Privacy Statement



Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter. Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.

Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.

OCR for page 21
21 CHAPTER FOUR ENVIRONMENT Survey participants were asked to identify the kind of problems Having a Category II/III instrument approach with center- they have encountered at airports relative to reduced visibility, line lighting and touchdown zone lighting makes it easier for seeing where they are on the airport, or the difficulties in nav- a vehicle operator to discern the borders of the runway and igating on the airfield when engaged in snowplowing, broom- one's position on the runway; however, most airports do not ing, deicing, or other winter operations. They were then asked have such capability. Finding either the runway centerline for to identify how they solved the problems. Their responses, as a beginning snow run or the sides of the runway or taxiway noted here, provide insight into the varied operations of dif- is a problem during winter operations because the pavement ferent categories of airports that have varied organizational markings and lighting may be obscured. Using the obstruction structures and resources. lights on the localizer for a position reference on the runway was a trick one operator used. Another operator used obstruc- VISIBILITY tion lights on buildings or other fixtures as a reference. All snow events present some measure of degradation in vis- ibility and SA. Blowing snow, whiteout and blizzard condi- MANAGING ENVIRONMENTAL CONDITIONS tions, blowing sand, heavy fog and precipitation, equipment blocking line of sight, and vehicle blind spots were factors There were a number of suggestions made by survey respon- cited by operators as affecting visibility. Outside the vehicle, dents regarding the most effective way to manage or address the accumulation of snow or snow banks obscuring signs and the problems brought on by wintry conditions or low visibility. lighting are major issues. To help with visual orientation, snow sticks mounted to edge lights are a common practice. Installing radius stakes around The speed of vehicles was cited as an issue by several air- taxiway curves before winter season helped on several airports. ports because it resulted in both accidents and incursions. The One airport put reflective tape on the ends of signs as a way time pressure to get the movement area cleared prompted the to help see where the signs are and for enhancing situational drivers to push their limits and the limits of their vehicles. positioning. However, locating signs or edge lights proves Unfortunately, higher speeds decrease driver reaction time difficult when, as another operator pointed out, the snow is so and increase braking distances, which increase the collision deep you cannot see either signs or lights. One airport operator risk factor on the airport. commented on the benefit of runway guard lights, which is an available technology mentioned in chapter ten: The use of runway and taxiway lights generated contra- dictory statements from operators as to which was the best Above ground runway guard lights (RGL or commonly called wig-wag lights) should be mandatory at all runway/taxiway inter- method. One large-hub airport always works with their run- sections. In-ground lighting and surface markings are often way lights at high settings so they can better see the airfield obscured during snow/ice events. Compacted snow and ice can signs that are connected to that circuit. However, a driver render those aids unusable for days following an event. from a small-hub airport commented that the runway lights are always very bright, even on the dim setting, making it hard Several operators said the key to not having an incident, to cut the edge very close because of the glare and disorien- incursion, or collision with another vehicle is simply to slow tation in the peripheral vision. One non-hub airport operator down the operation as visibility declines. Maintaining proper requests that the runway lighting be turned down, but not off, distance from other vehicles was important and lighting on so that drivers are not blinded by the intensity of the airfield the rear of vehicles helped that purpose. This is supported in lighting. In contrast, the procedure at another airport is to the literature search (35). turn off the runway lights as a means to eliminate confusion to pilots and reduce the risk of aircraft use. However, the lack We lead our snow teams with our most experienced operations of runway edge lights compounded the lack of visual cues for staff. Most of the staff have over 20+ years working on the air- the snow crew. To illustrate how limited visibility and poor field, and they always know where they are. We also have the latest equipment with our runway snow teams. These vehicles lighting can be confusing, one operator described a situation are lit up like a winter holiday, and are easily seen in poor visibil- where a driver lost track of which side of the runway light he ity conditions. They also have the best deicing capabilities like was oriented toward and ended up driving into the safety area. heated windshields, etc.